


This Is Penance

by elliotwritesgarbage



Category: The Last Hours Series - Cassandra Clare, The Shadowhunter Chronicles - All Media Types, The Shadowhunter Chronicles - Cassandra Clare
Genre: Anal Sex, Guilt, M/M, Masochism, No Lube, Not Beta Read, Painful Sex, Self-Hatred, Self-Indulgent, Shame, Spoilers, but like in a hot way?, could be read as dubcon so be careful, really gross porn, so much hot hot shame, thomas is hung
Language: English
Status: Completed
Published: 2021-03-05
Updated: 2021-03-05
Packaged: 2021-03-18 03:55:31
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,965
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29852196
Author URL: https://archiveofourown.org/users/elliotwritesgarbage/pseuds/elliotwritesgarbage
Summary: *SPOILERS*Thomas and Alastair have a moment in the Sanctuary, and things get heated. Alastair, feeling guilty, decides that if Thomas is going to fuck him, he doesn't deserve to enjoy it. Kind of like penance.Probably can be read like dub-con but it's really more like. Forcing yourself into sex and feeling ashamed about liking pain? Either way, be careful.
Relationships: Alastair Carstairs/Charles Fairchild, Alastair Carstairs/Thomas Lightwood
Comments: 1
Kudos: 50





	This Is Penance

**Author's Note:**

> So this is really self-indulgent and fits a very specific niche in my brain. Crushing shame, being used like a toy, innocence about sex, and turning a good boy into a sex hungry monster are very appealing to me, okay?
> 
> Can you tell I'm working through some stuff?

Alastair couldn’t help but think back, over and over, to something Thomas had said. “You richly deserve to be hated for what you have done.” It had not been said in anger, but in a calm, level tone, not daring to shatter the stillness of the room. Though it was lit entirely by candles, the light seemed steady on Thomas. There was no questioning if he was right: he was. The question was then why when he so deserved it, did Thomas refuse to do so?

In his younger days, he might have said it was to cause him fury. To force him to bask in his shame, made worse that it was one-sided, and that he spent no time in the mind of Thomas Lightwood. Thomas, with everything Alastair lacked -- loving parents, money, political influence, the Consul at his beck and call, and friends who seemed to like him simply for the fact that he existed -- must have an easy time with being kind. It was easier to think that it was a passive consequence and not a choice. The realization of the opposite had acted like an earthquake under Alastair. All at once, he felt his foundations crumbling and a dam spilling and everything going to ruin under the stress of his imploding shame. 

And then Thomas had kissed him. It hadn’t stopped the feelings but intensified them, and pulled them into a consuming need for Thomas. He fed all of these feelings without knowing it, the guilt twisting his guts, the shame making him want to run, the fear of his own vulnerability angering him and making him desperate to lash out, to slice Thomas down once more and remind him exactly why he should be hated. Thomas fed his desire most, and when Alastair had him by the shirtfront it was almost accidental. 

Thomas was naive and inexperienced. His hands did not smoothly travel down Alastair’s body, but the clumsy movement of hands so big made him want to climb into Thomas’s lap. He pressed closer, their knees bumping together, and he realized that Thomas was sitting back on his heels and still so tall that Alastair, on his knees, had to tilt his head to kiss him. 

Alastair felt Thomas’s hand reach up into his hair, and wrap around the strands with a satisfied sigh like he had been wanting to do it for hours. It had been months since he had been touched at all, and it had never been like this. Thomas’s fingers gently pulled at his hair -- his dark hair, that Thomas had complimented him on. He was so unlike Charles, who always found him embarrassing, foreign, too obviously an outsider. It was Thomas who had told him he hadn’t suited his bleached hair, who looked at his dark eyes with desire so strong it nearly sent him to his knees. It was Thomas who had begun kissing the brown skin of his neck so delicately it felt like praise. Alastair moaned, and clapped his hand over his mouth.

Thomas broke away, panting very hard. There was no mockery in his voice when he asked, “Did it feel good?” 

The innocence of his voice nearly broke Alastair, and he groaned out “yes”, before falling backwards, pulling Thomas down on the makeshift bed with him. Why had the inquisitor even thought to give them two beds? Surely it would have been a better punishment to have them share, two boys who hated each other and hardly fit on the mattress by themselves. 

The weight of Thomas over him felt entirely different than Charles. He was trying his best not to crush him, to be aware of his hulking body and how it might injure someone smaller. Someone powerless, Alastair thought and shuddered.

All his life, so desperate for control over his reputation, terrified to be made to be weak. It was shattering under Thomas’s weight. Thomas, a half-foot taller and muscular to the ideal of strongmen and Greek gods. Alastair remembered seeing David in person. At 14 he had stood in front of that statue with his mother and sister, feeling the crushing grip of arousal for the first time. Shame had quickly followed, and his cheeks had burned for what seemed like hours. Another thing wrong with him. Another thing to hide with cold anger.

Had he known Thomas would grow up to look this way he may have been nicer. He may have also been crueller, he told himself, because Thomas was beautiful to the point of pain, and every bit a better man than he. He could hardly look at him for the shame, and hardly bear to look away. 

He moved to switch positions and Thomas willingly obliged him. They began to roll, and just as Alastair began to feel the hard press of Thomas’s erection against him, they fell to the floor. Thomas hit the floor with his shoulder first and rolled the rest of the way onto his back. Alastair scrambled off of him. 

Alastair couldn’t tell why his cheeks were burning. He thought it might be shame, and his eyes flicked up to Thomas’s face to gauge his reaction. Thomas was bright red, his short brown hair mussed and his eyes shining with excitement. Ah.

Instead of apologizing, Alastair said, “I’m starving,” and deliberately busied himself with the food trays. It might take him weeks to understand all he was feeling; every new emotion opened up under his scrutiny and unfolded into a thousand new ones, calling up memories so quickly his head spun. Just eat, he told himself, and don’t let Thomas see your hard-on.

“You know,” Thomas said after a few silent bites of cold chicken, “my friends always joke that feeding me is like feeding a horse. I think Briget remembered that when she sent the food.”

There was a lot of food for one night (it was only meant to be one night, right?) but Thomas was so big he probably could eat it all himself. He never would allow himself to do that if he thought someone else was hungry though, would he? Bastard. 

“We are only meant to be in here for the night, right?” Alastair said, still not looking at Thomas. 

Thomas made a noise of agreement through his full mouth. “That’s what Bridgestock said. Although I don’t know how much longer that will be. Or how long we’ve been here already. I’m afraid I’ve quite lost track of the time already.”

Thomas had been here longer than him, he knew that. He had seen him bound to a chair, and handcuffed, which seemed excessive to Alastair. Sure he was large, but he wasn’t a monstrous giant. He briefly considered how it might be if the inquisitor had seen fit to leave him tied to a chair, and shook the thought from his head. It did nothing to calm the urgency in his gut. 

“Lucky thing your friends arrived to cut your bindings away.” Alastair tried to keep his voice neutral, but he felt the sneer creep through.

“Lucky thing.”

Fuck. After a few moments, Alastair tried again. In the spirit of sharing, which they had seemed so eager to do just a little while ago. 

“You know, in Persia, apples are used as a symbol of the new year.” Alastair cut a slice from the red apple in his hand with the dull cheese knife they’d been given. “They’re called seeb and they’re meant to represent beauty.”

“You must have had apples in abundance this year.” 

It wasn’t as clever as anything Matthew could have come up with, nor was it anything he hadn’t heard before. It was the sincerity of Thomas’s face -- his genuine belief that Alastair was beautiful, and the gentle joking tone he’d used -- that nearly undid him. He might have cried, so instead, he bit into the slice of apple, swallowed, and licked the juice from his lips. Thomas’s eyes widened. He looked hungry. 

Alastair had seen that look before, from men, from women, from demons, and never once had it shot through him in this way, sending energy down his spine and heat through every nerve in his body. Thomas was looking at him as prey, and Alastair wanted to be caught.

He threw the other piece of apple to the floor just as Thomas’s hand wrapped around the back of his head and pulled him in for a kiss. It was rougher than he expected, forcing his lips open in a ragged gasp. Thomas was able to handle him so easily, dragging him closer and holding him tight. 

He seemed to have unleashed something desperate in Thomas, something primal. Something shy, innocent, inexperienced Thomas would flush at the thought of. He wasn’t sure if Thomas had ever even kissed anyone before. If he had, surely not another man. 

Thomas’s long fingers stroked through his hair with a gentleness that, given the vice grip on his waist would have seemed laughable if it didn’t pull a soft whine from him. Thomas seemed to like that, and tightened his hand in Alastair’s hair, pulling just hard enough to tilt his head back.

Guilt rushed up at him again, rising in his stomach so powerfully he wanted to break away. No matter how badly he wanted to, he knew he couldn’t. He had gone boneless, and it didn’t seem to matter that he’d had a life of training. He was caught up in strong arms and stronger desire and his guilt wouldn’t let him move. He had never seen Thomas give in to his baser instincts, always in the name of goodness. If he knew he was hurting Alastair, he would stop. He couldn’t know.

Thomas pushed him towards the mattress, and Alastair fell back on it easily, eager to feel a weight other than shame crush him. Thomas came down hard on him, keeping him in place while he went after Alastair’s neck. He still had a hand in Alastair’s soft dark hair and was using it to keep his neck exposed. 

His kisses were rougher this time, wetter and louder, and a few times he even bit down gently. Alastair couldn’t hold back a moan. His hips tried to buck upwards, and he ground his cock into Thomas’s. Thomas stifled a groan into Alastair’s neck. 

Thomas began to move slowly, rocking his hips into Alastairs, and panting in a way that told Alastair he had never done this before. 

Another wave of guilt crashed into Alastair. How badly had he manipulated Thomas to bring him this far? Virtuous Thomas had probably never even touched himself, and now Alastair was dragging him into this sinful depravity so far from self-control that Thomas seemed to have turned into an animal. He probably fantasized about getting married still and saving himself for his spouse. As if it were possible for anyone like them. Why not give him one more reason to despise Alastair? He wanted to despise him. He had said it himself. 

Alastair freed his arms from where Thomas had pinned them and reached up to yank Thomas’s shirt from his trousers. There was no space between them to unbutton, but Alastair slid his hands under that cotton fabric and took a moment to be silently thankful that Thomas wore separates before reaching under his undershirt. Thomas’s back was broad and warm, and his every slow thrust made his muscles shake under Alastair’s hands, so desperate was he to control his pace. 

Suddenly Thomas pulled away, sitting back with his on either side of Alastair’s hips. A feeble apology rose to Alastair’s lips but died in his throat when Thomas began to undo the buttons on Alastair’s shirt. 

Alastair hated to speak. “We might leave them on, in case we find ourselves interrupted.” His voice was hoarse and weak even to his own ears. If only, he thought, if only Thomas saw fit to stuff his mouth so that he might never spread any lies again. If only he would abuse his throat until tears ran down his face and he couldn’t breathe for gagging. Such a punishment might be suitable penance for the thought even crossing his mind. 

Thomas nodded and undid his own buttons anyway. Under normal circumstances, seeing Thomas in shirtsleeves was enough to make Alastair’s throat dry. He could see collarbones and the line just above them where his skin went from gently tanned to pale. There was a strip of stomach exposed where his shirts had been rucked up, with gentle rises and valleys between abdominal muscles, and the lightest dusting of hair just above the line of his trousers. He had taken off his braces hours ago, and the dark wool trousers were sliding from the rutting.

When he finally managed to look Thomas in the eye once more, Thomas was already leaning forward again. His brown eyes were half-lidded and dark with desire, and his soft mouth was bright pink and shining just so, and then they were kissing again, more gently this time but somehow more lewd, sliding together with wet lips and soft tongues. Alastair thought he might be consumed entirely by this feeling, the desire filling the cracks in his shame and driving him so far into his own need that he may not have noticed if the Consul walked in then and there. 

He might deserve that too, to be faced by the two highest authorities in the Clave and the heads of the institute while he lay there, getting ravaged by someone better than him in every way. No doubt they would blame him, as he blames himself, for enticing Thomas into this like a bitch in heat, infecting Thomas with his vulgarity. Poor virginal Thomas, falling victim to his wicked games.

He felt a hand between their bodies and felt Thomas struggling with the buttons on his pants. Alastair gently replaced Thomas’s hand with his, and expertly freed each button with ease. Thomas moaned into his mouth in relief when he was finally free, and pushed himself into Alastair’s hands. 

Alastair’s eyes flew open when he felt it. Through his thin drawers, he could feel the weight of him. His cock was heavy and thick and as he humped Alastair’s hand like a dog Alastair could feel its length, too. Thomas could tear him in half. 

He had passively thought of this already, ever since he’d seen with his own eyes the evidence of Thomas’s growth spurt, and the thought had always filled him with morbid curiosity. He understood Thomas’s moan of relief now, his stiff trousers must have been almost painfully tight. 

Before he lost his nerve, Alastair began to undo his own buttons. Thomas barely slowed his rhythm, desperate for this friction on his poor neglected member. He wondered if Thomas had ever allowed himself this pleasure before. He’d wondered about it before, too, while he jacked his spit-slicked cock in desperate need to finish before the guilt set in. He’d thought of Thomas, pink-faced and lying in his bed, both hands wrapped around himself while he tried to stifle his whimpers by biting his lip. He’d thought of getting to put his mouth on it, swallowing him down and hear him cry out in surprise, and wrap Alastair’s hair around his fingers and use it to control him. More often than not, it was the thought of Thomas pulling him off, and finishing on his face that made him finally shudder and spill his load. 

With some difficulty, Alastair slid down his trousers and drawers in one movement. Thomas had managed to shove down his drawers enough to free himself, and both boys moaned when they finally felt the warm soft slide of skin against skin. Alastair tried to hold them both in his hand, pressing them together while Thomas ground into him, but Thomas was too big. 

It wasn’t enough. Thomas should get to fuck properly. He was still happily rocking against him, grunting into Alastair’s neck and panting like a dog. He really had turned him into an animal. Before any more shame could come, Alastair considered the options. Of course, there was no petroleum, which had been Charles’ method of choice. The salad they had been brought had had oil and vinegar on it already. 

Alastair steeled his nerves and spat into his hand. He was shaking slightly when he gripped at Thomas’s cock and began to stroke. Thomas gasped and shuddered, his hips faltering in their steady rhythm. He seemed about to cum, and Alastair was impressed he had lasted this long. To his surprise, Thomas pulled his face away from Alastair’s neck to look into his eyes.

“What--” he began to ask, but stopped short when Alastair said:

“Please.”

Thomas nodded, and allowed Alastair to wiggle his trousers further down his legs, and then off one of them. Better to have them readily available just in case... 

Alastair brought his other hand to his face and sucked two fingers into his mouth. He heard the gasp from Thomas while he watched, and Alastair moaned quietly. He still wished he could get his mouth on Thomas’s cock, get his throat fucked by such a monstrous appendage, and taste his huge, hot load. If there was going to be another time, maybe he could ask for that. 

He let his mouth fall open with another moan. Thomas twitched in his hand at the sound. He wouldn’t keep Thomas waiting. He pushed a finger into himself hastily and hissed. The saliva had gone cold, and it was far less slippery than he was used to. Still, he fucked himself gently with it for just a moment. He pushed in his second finger and found his prostate though habit alone. He forced himself away from it after his moan. That touch had sent new pleasure through his body, drowning out his apprehension. Thomas’s eyes were locked on his face while he fingered himself, his soft mouth open in awe of the display Alastair was putting on. 

Alastair spread his legs as best he could, and let go of Thomas’s dick. By some virtue, Thomas seemed to understand what he wanted; he planted himself firmly between Alastair’s bare thighs. Perhaps it was a result of the ropes of his bolas, or by some other miracle, Thomas’s hands were rough and callused and seemed to scratch at Alastair’s thigh when he stroked over it. 

Alastair reached down, and took Thomas in his hand once more. Gently, he brought it to his barely-stretched entrance without looking. If he looked, he might back out. And he thought he probably deserved this. 

Thomas seemed to understand. He leaned forward once more, their faces inches apart, and stared into Alastair’s eyes while he pressed forward. 

At first, it was strange. Alastair felt the wet, spongy head of Thomas’s cock press against him and tensed -- and then forced himself to relax. As soon as it breached his entrance, he seemed to shatter into pieces. The saliva Alastair had used to slick them up had not been nearly enough. He choked down a howl and it became a whimper, his hips moving instinctually to try and get away, but he could go nowhere with so much of Thomas on top of him. 

Thomas paused, his eyebrows drawn in concern until Alastair wrapped a leg around him and began to push him in deeper. Those sweet brown eyes rolled back to the whites and he let out a deep, satisfied groan. Alastair spat into his hand once more and wrapped it swiftly around the rest of Thomas. His eyes shut in defeat when he felt how much there was still to fit inside of him. 

Thomas seemed to be able to push in more easily though and used it to his advantage. Alastair bit down hard into Thomas’s shoulder and he felt himself be torn in two. He muffled a wail against the fabric and solid mass while Thomas bottomed out and paused, revelling in the feeling of Alastair squeezing him so tightly. 

Alastair’s erection had begun to flag from the pain. And then Thomas began to withdraw, just a little bit, and push back in. Thomas’s moans were sweet and dirty and it might have made it all worth it on its own, but then the head of Thomas’s cock brushed against Alastair’s prostate and he sobbed, still muffled, into his lover’s shoulder.

Seeming to have gained confidence, Thomas began to fuck him faster. He chased his orgasm recklessly, leaving no thought for Alastair just -- as Alastair reminded himself -- just like he deserved. 

He wondered if this was rage, the way Thomas was punishing him, ripping him apart and stretching him over his cock. Using him as a toy to be discarded afterwards, fucked out and stuffed with cum.

Good, Alastair thought. If this is anger, be angry. For yourself this time, not for Matthew. Punish me for how I’ve behaved. Make me atone. 

He raised his arms to Thomas’s back and dug in, no doubt leaving dents where each of his nails nearly broke the skin. Thomas grunted with shock but kept going, doubling his pace. Alastair let up on Thomas’s shoulder, realizing it wasn’t doing much good to keep him quiet. His muffled whimpers had turned into high-pitched, throaty whines he had never heard himself make before. 

He couldn’t tell if it felt good or if it was agonizing, but he had become hard again despite the pain. Hot shame rose in him once more, bringing tears to his eyes and even more blood to his face. He was enjoying it. He was a whorish degenerate, about to cum from being split open and used by Thomas Lightwood. 

Sanctimonious Thomas Lightwood had been made to debauch himself at the whims of a wanton sinner as penance for that libertine, except it was no penance at all. He was drooling for it. He reached down for his cock and began to stroke himself, and he felt himself clench down on Thomas. Thomas howled -- and quickly bit into his lip to stop himself. He looked into Alastair’s eyes, and it was enough to push Alastair over that edge. He bore down on Thomas while his every muscle tightened in anticipation. Silently, Alastair spilt his load between them, not daring to do so much as breathe for fear of wailing, or worse, confessing all. 

Thomas’s hips stuttered and lost their careful rhythm. He swore under his breath while his orgasm ripped through him. He pushed himself impossibly deeper, causing painful ecstasy to shoot through Alastair’s exhausted body. It seemed to last forever. He panted and groaned, his breath catching and hitching while he shot ropes of seed deep into Alastair, over and over again. 

As soon as it was over, sluggishness flooded his massive body. He was suddenly unable to hold himself up, and all of his weight fell onto Alastair. He hadn’t realized how much Thomas was holding himself until he went boneless on top of him. The weight was comforting, though it shortened his breath, and part of him wished to stay like that. He could feel Thomas inside of him, still hard but beginning to soften. There was a warm wetness as well, and the thought sent a thrill through him.

Lying like this, he could almost pretend it was normal. This could be their bed. Maybe, if they could forget everything but Paris, like Thomas had said, then they could be like this. How he and Charles were meant to have been. Cuddled together on their bed, having just made love.

Alastair was brought back to reality when Thomas shifted, and slid out gently. An arc of white-hot pain shot through Alastair and he remembered: this is penance.

**Author's Note:**

> no beta we die like men


End file.
